1. Field of the Invention
The present invention relates in general to a mobile communication system, and more particularly to a method for formatting a signal in a mobile communication system.
2. Description of the Prior Art
A conventional method for formatting a signal in a mobile communication system will hereinafter be described with reference to FIGS. 1a and 1b. 
FIG. 1a is a view illustrating a data flow for a non-automatic repeat request (ARQ)-type radio access bearer service to which the conventional signal formatting method is applied, and FIG. 1b is a view illustrating a data flow for an ARQ-type radio access bearer service to which the conventional signal formatting method is applied.
A medium access control (MAC) sublayer of a mobile station utilizes a MAC-protocol data unit (PDU) for peer-to-peer communication with a peer MAC sublayer of a network.
The MAC-PDU contains fields necessary to the execution of a MAC function.
In radio link control-user/control plane (RLC-U/C) layers, data transferred from upper layers is segmented into payload units (PUs) and then reassembled.
The PU is defined as a unit for the resending of an ARQ-type service, and it is dimensioned to be suitable to the lowest data rate in connection.
The RLC-U/C layers append headers for segmentation information and acknowledgment information respectively to the PUs and transfer the resultant RLC-U/C PDUs to the MAC sublayer.
The MAC sublayer, in turn, appends information multiplexing headers respectively to the RLC-U/C PDUs from the RLC-U/C layers and produces the resultant MAC-PDUs.
The MAC-PDU has a size corresponding to that of a transport block to a layer 1.
On the other hand, a non-ARQ-type variable rate service, the MAC-PDU is mapped into a transport block to be transferred to the layer 1, the size of which is variable.
As a result, in the non-ARQ-type variable rate service, the MAC-PDU is variable in size. As shown in FIG. 1a, the MAC-PDU includes a plurality of MAC-service data units(SDUs).
In an ARQ-type fixed rate service, the MAC-PDU is determined in size according to the size of a transport block where the PU is fixed in size. As a result, the MAC-PDU includes only one MAC-SDU, as shown in FIG. 1b. 
As shown in FIG. 1a, a physical layer transforms one multiplexing header and one MAC-SDU or one multiplexing header and a plurality of MAC-SDUs from the MAC sublayer into a transport block with a predetermined size. Also, as shown in FIG. 1b, the physical layer transforms one multiplexing header and one MAC-SDU from the MAC sublayer into a transport block with a predetermined size. Then, the physical layer sends the resultant transport block to the network through a physical channel.
Upon receiving the transport block sent from the mobile station through the physical channel, the network performs the opposite procedure to that of the mobile station to separate the received transport block into one MAC header and one or more MAC-SDUs and perform the associated signal processing.
Therefore, the present invention has been made for the effective implementation of a medium access control sublayer function, and it is an object of the present invention to provide a method for formatting a signal in a mobile communication system, in which a medium access control sublayer formats medium access control-protocol data units according to transport channel characteristics in peer-to-peer communication in such a manner that the protocol data units can have different formats with respect to different transport channels.
In accordance with one aspect of the present invention, the above and other objects can be accomplished by a provision of a method for formatting a signal in a mobile communication system by appending a plurality of medium access control headers to a plurality of medium access control-service data units for data transfer between a mobile station and network in the mobile communication system, comprising the first step of, if the service data units have the same characteristics, forming a medium access control-protocol data unit by successively coupling the service data units to any one of the medium access control headers; and the second step of transforming the formed protocol data unit into a transport block with a predetermined size.
Preferably, the protocol data unit may include a plurality of fill bits.
Further, preferably, each of the medium access control headers may include a mobile identifier region for in-band identification; a medium access control-service access point identifier region for multiplexing a logical channel for service data with a corresponding one of the medium access control headers; a radio link control-user plane identifier region for multiplexing a radio link control-user entity; a medium access control-service data unit length region and a medium access control-service data unit extension region or a medium access control-service data unit number region for cooperating to send the service data; and a frame format identifier region for transfer of information to a higher layer and contention resolution.
Further, preferably, the frame format identifier region may include an information format for transferring the information to the higher layer; and a command format or a response format for the contention resolution.
In accordance with another aspect of the present invention, there is provided a method for formatting a signal in a mobile communication system by appending a plurality of medium access control headers to a plurality of medium access control-service data units for data transfer between a mobile station and network in the mobile communication system, comprising the first step of, if the service data units have different characteristics, forming a medium access control-protocol data unit by sequentially coupling each of the service data units and each of the medium access control headers; and the second step of transforming the formed protocol data unit into a transport block with a predetermined size.
Preferably, the first step may include the step of sequentially forming the medium access control headers and then appending each of the service data units to a corresponding one of the medium access control headers subsequently thereto.
In accordance with yet another aspect of the present invention, there is provided a method for formatting a signal in a mobile communication system by appending a plurality of medium access control headers to a plurality of medium access control-service data units for data transfer between a mobile station and network in said mobile communication system, comprising the first step of, if said service data units have the same characteristics, forming a medium access control-protocol data unit by successively coupling said service data units to any one of said medium access control headers; the second step of, if said service data units have different characteristics, forming said protocol data unit by sequentially coupling each of said service data units and each of said medium access control headers; and the third step of transforming the formed protocol data unit into a transport block with a predetermined size.
In a feature of the present invention, a medium access control sublayer formats medium access control-protocol data units according to transport channel characteristics in peer-to-peer communication in such a manner that the protocol data units can have different formats with respect to different transport channels. This makes it possible to provide more efficient functions.